1. Field of the Invention
The present invention relates to motors having coils through which high currents pass, more particularly, to motors having armatures using U-shaped conductors.
2. Description of the Related Art
Motors for driving heavy machines such as industrial machines gain the necessary power by passing a high current of 100 A or more through conductors. The conductors for use in a motor requiring a high current are too thick to be wound circularly around a magnetic pole of an armature core by a coil winder. The conductors are therefore bent into a U-shape by, e.g., a machine press in advance and then attached to the armature core.
Japanese Unexamined Patent Publication No. 2004-32964, for example, discloses a technique of attaching a spacer at the ends of approximately U-shaped segment conductors to align the segment conductors with a predetermined spacing in between.
Generally, when high currents are applied to conductors, a great amount of heat is generated due to the electric resistance of the conductors, which heat is accumulated excessively within the motor. The conductors to be attached to the armature therefore require a heat dissipation structure that, e.g., provides spacings between adjacent conductors.
In Japanese Unexamined Patent Publication No. 2004-32964, however, the ends of the segment conductors are positioned uniformly at a certain axial level, and thus the circumferentially adjacent segment conductors have their ends arranged close to one another. This structure disadvantageously hinders heat dissipation of the segment conductors.
Moreover, since the spacer is coupled only to the segment conductors, the insertion positions of the segment conductors determine the position of the spacer. Therefore, a jig and the like have to be used to locate the segment conductors axially, which complicates the manufacturing process of the armature.
Further, the above technique is not applicable in the case where the conductors are so thick that they need to be bent by a machine press or the like. Thus, Japanese Unexamined Patent Publication No. 2004-32964 is only suitable for armatures with conductors having a relatively small thickness, i.e., armatures to be applied with low currents, but not for armatures to be applied with high currents with conductors having a large thickness.